Nicene and Post-Nicene Fathers, Vol. V:A Treatise on the Spirit and the Letter.: Chapter 16

Because “for a righteous man the law was not made;” 765
and yet “the law is good, if a man use it lawfully.” 766
Now by connecting together these two seemingly contrary statements, the apostle warns and urges his reader to sift the question and solve it too. For how can it be that “the law is good, if a man use it lawfully,” if what follows is also true: “Knowing this, that the law is not made for a righteous man?” 767
For who but a righteous man lawfully uses the law? Yet it is not for him that it is made, but for the unrighteous. Must then the unrighteous man, in order that he may be justified,—that is, become a righteous man,—lawfully use the law, to lead him, as by the schoolmasters hand, 768
to that grace by which alone he can fulfil what the law commands? Now it is freely that he is justified thereby,—that is, on account of no antecedent merits of his own works; “otherwise grace is no more grace,” 769
since it is bestowed on us, not because we have done good works, but that we may be able to do them,—in other words, not because we have fulfilled the law, but in order that we may be able to fulfil the law. Now He said, “I am not come to destroy the law, but to fulfil it,” 770
of whom it was said, “We have seen His glory, the glory as of the only-begotten of the Father, full of grace and truth.” 771
This is the glory which is meant in the words, “All have sinned, and come short of the glory of God;” 772
and this the grace of which he speaks in the next verse, “Being justified freely by His grace.” 773
The unrighteous man therefore lawfully uses the law, that he may become righteous; but when he has become so, he must no longer use it as a chariot, for he has arrived at his journeys end,—or rather (that I may employ the apostles own simile, which has been already mentioned) as a schoolmaster, seeing that he is now fully learned. How then is the law not made for a righteous man, if it is necessary for the righteous man too, not that he may be brought as an unrighteous man to the grace that justifies, but that he may use it lawfully, now that he is righteous? Does not the case perhaps stand thus,—nay, not perhaps, but rather certainly,—that the man who is become righteous thus lawfully uses the law, when he applies it to alarm the unrighteous, so that whenever the disease of some unusual desire begins in them, too, to be augmented by the incentive of the laws prohibition and an increased p. 90amount of transgression, they may in faith flee for refuge to the grace that justifies, and becoming delighted with the sweet pleasures of holiness, may escape the penalty of the laws menacing letter through the spirits soothing gift? In this way the two statements will not be contrary, nor will they be repugnant to each other: even the righteous man may lawfully use a good law, and yet the law be not made for the righteous man; for it is not by the law that he becomes righteous, but by the law of faith, which led him to believe that no other resource was possible to his weakness for fulfilling the precepts which “the law of works” 774
commanded, except to be assisted by the grace of God.